When treating the gummy smile with Botox, there should be no change in the shape or appearance of the upper lip. The ideal treatment is to keep the beautiful smile, just with a little less show of the gums. If the treatment is overdone, then the upper lip can appear to lengthen and look flat. As we age, there is also a natural lengthening of the upper lip even without Botox due to loss of support and some laxity of the skin. So the best candidates for Botox treatment of the gummy smile are those who have a youthful lip to begin with. Botox treatment for gummy smile lasts a few weeks and rarely more than a couple of months. Nevertheless, when performed correctly, it can provide very satisfying results.